It is known that the water vapor pressure above concentrated water-salt solutions of, for example, calcium chloride, lithium chloride or lithium bromide or the like and/or mixtures thereof is lower than that of pure water at corresponding temperature, and that these solutions can be therefor used as water-absorption liquids.
According to one aspect of the present invention a circulating water stream which takes up and carries away heat from a heat exchanger is caused to expand at reduced pressure in a flash tank. An amount of water vapor corresponding to the temperature drop, i.e. the absolute pressure, is then released. The water vapor released by expansion in the flash tank is introduced into a condenser having cooled surfaces which are continuously wetted by a water-absorbing concentrated salt solution. Water vapor is absorbed by the salt solution or condensed into it as long as the water vapor pressure above the salt solution is lower than the pressure of the vapor released by the expansion from the flash tank. It is thus possible to condense water vapor in a salt solution having a temperature which is about 20.degree. C. or more above the saturation temperature of the water vapor.
The present invention thus utilizes the low water vapor pressure above a concentrated salt solution for allowing a saturated water vapor to be absorbed in a salt solution having a higher temperature than the absorbed water vapor.
It is another object of the present invention to provide a method and apparatus for cooling a fluid such as, for example, an absorption liquid used to dehumidify and cool a gas such as air in an air conditioning apparatus.